Airplane structural element



July 1, 1941.

J. B. THOMSON Re. 21,850 AIRPLANE STRUCTURAL ELEMENT Original FiledMarch 29, 1937 2 Sheets-Sheet 1 JohnB. Tho7nsq July 1, 1941- J. B.THOMSON AIRPLANE STRUCTURAL ELEMENT Original Filed March 29, 1937 2Sheets-Sheet 2 Reissued July 1 1941 Serial No. 133,707, March 29, 1937.

Application for reissue April 29, 1941, Serial ,No.

3 Claims. (Cl. 244-124) This invention relates to improvements inairplane structural elements such, for example. as

fuselages, wings, tail surfaces, flying boat or am-.

phibian hulls,seaplane floats and the like, and has for its generalobject to provide such elethey are formed sectionally they preferablyare ments at greatly reduced cost and in a form having numerous inherentadvantages as compared with the cost and the form of corresponding eleofa solvent.

provided with suitable mating formations whereby they may readily befastened together in unitary form, either by means of bolts, screws,glue, cement or the like, or by fusion through the use Regardless ofwhether they are .formed sectionally or as complete, one-piece merits,provided according to present general practice, particularly to the endof enabling the low cost, quantity production of airplanes havingvarious features of advantage over airplanes produced in accordance withpresent general practice.

Heretofore, airplane structural elements, such as those mentioned, have,as a general rule, been fabricated from ribs, stringers, bulkheads,braces,

former gusset-plates, skins or walls and the like, welded, riveted.bolted, screwed, nailed, glued or otherwise fastened together-usually byskilled hand labor. Production costs have as a consequence, beenextremely high. Moreover, despite the care exercised in designing andfabricating such elements, it has proved to be very difllcult toapproximate complete, ideal streamlining of the same, due to thedimculties experienced in attempting to avoid sharp angles at comers andother locations. Furthermore, when bolts, rivets or screws have beenemployed as fasteners, the heads of the same have disadvantageouslyprotruded beyond the outer faces of the structural elements.

According to the present invention, airplane structural elements such asthose mentioned are moulded, cast,- pressed or otherwise formed, eithersectionally or as complete one-piece units, including all necessaryreinforcements, from plastic material. Thereby, production costs aregreatly reduced; the elements may be standardiaed for economicalquantity production, and higher aerodynamic eillciencies may be obtainedbecause of the practicability of ideally streamlining the elements andproviding them with smooth exterior surfaces. In addition, numerousother advantages inherently are obtainedsuch for example, as stability,strength, vibration and sound dampening, and flreprooilng and resist--ance to acids and the elements when the plastic employed 1;, of afireproof. acid and element reslstlng nature.

units, theyare provided internally, with integral ribs, flanges or thelike, wherever necessary and in any desired relationship, to impart tothe elements all requisite stiifness and strength.

In the accompanying drawings, which are i1- lustrative of the invention:

Figure 1 is a perspective view of a portion of I an airplanefuselageformed sectionally in accordance with the invention, thesections being shown in separated relationship.

, Figure 2 is a cross section through the structure shown in Fig. 1.

' Figure 3 is an enlarged detail perspective view of a fragment of thestructure shown in Fig. 1.

Figure 4 is a perspective view of a portion of a seaplane float formedsectionally in accordance with the invention.

'Figure 5 is a perspective view of aportion of an aircraft wing formedsectionally in accordance with the invention; and

Figures 6, "i and 8 are detail sectional views illustrating somedifferent types of mating formations with which related edges of thedifferent sections may be provided.

It will be understood, of course, that the fuselage, float and wingelements shown in the drawlugs and each designated generally as It, Eand E, respectively, are representative of various other airplanestructural elements which may be moulded, cast, pressed or otherwiseformed from suitable thermo-plastic material, either sectionally or inone-piece, in accordance with the invention.

In thepresent instance the fuselage element E is illustrated as beingcomprised by duplicate half-sections e, eto be fastened together in anysuitable mannerto form the complete unit. Each section e comprises askin or wall ll of any suit able thickness stiffened and reinforced byinternal ribs or flanges II and having, preferably a'smooth outer faceof desired streamline shape, the flanges ll beingintegral with said walland of any suitable thickness and depth and being disposed in anysuitable relationship to each othc and the spars rigidly together. II isprovided and other sections e extend from illustrated in either of Figs.6, 7 or 8 or many baked under pressure to afford homogeneous structuresof great strength and rigidity. However, many of the disadvantagesheretofore mentioned in respect to the general prior practice areinherent to the forming of structural elements from laminations orlayers of plastic material impregnated with a phenolic condensationproduct other suitable manner to be fastened together either by bolts,'screws, glue, cement or the like,

or by fusion through the use of a solvent or by heat or in any othersuitable manner. In this connection the sections may, for example, beformed at their adjacent edges with 'interfltting tongues and grooves asgenerally indicated at l2- in Fig. 7, or with overlapping formations asgenerally indicated at I3 in Fig. 8, or with interen.

gaginghook formations as generally indicated at H in Fig. 9. f

The seaplane float E shown in Fig. 4- is illustrated as being formedsectionally both longitudinally and transversely and as being composedof more than two sections transversely as distinguished from thehalf-section fuselage element construction shown in Fig. 1. Obviously,

' ribs, flanges or the like composed of the plastic material itself forstiffening and reinforcing purthe fuselage element E or any similarelement may be sectionally constructed in the manner of the seaplanefloat shown in Fig. 4, or the latter, or any similar element, may besectionally constructed in the manner of the fuselage element shown inFig. 1, employing any of the joints illustrated between the sections.

Figure 5 of the drawings illustrates a practical manner of sectionallyforming an aircraft wing in accordance with the invention. Front and'rear wing spars "hand I! of I-section are provided having the free endportions of their top and bottom flanges I8 directed'downwardly andupwardly, respectively, as indicated at I9, and top and bottom elementse formed in accordance with the invention as heretofore described, spanthe space between said spars and have front and rear marginal portionsoverlying and underlying said top and bottom flanges, respectively. Inaddition, said elements a have ribs or flanges "abutting the portions IQof the spars whereby the latter are held properly spaced apart andwhereby bolts, rivets or other suitable fasteners may be employed bybeing'passed through said flanges 20 and portions Is to secure thesections A nose block said nose block to the front spar l6, these lattersections being securedat their rear ends to said front spar in the samemanner as the sections first mentioned and being secured at theirfrontends to the nose block 2| in any suitable manner Other sections e aresecured at their front ends to the rear spar in the same manner as thefirst mentioned sections and at their rear ends said last mentionedsections are fastened either directly together or to a strip 22 theequivalent of the nose block 2|. Alternatively, the sections 6 inadvance of the front spar and behind the rear spar may, if desired, beof one-piece construction.

In any event, the wing is, 'or may be, of smooth exterior form and,generally speaking, embodies all of the essential features of theinvention described'in connection with Figs. 1 to 4.

It is known that airplane structural elements have heretofore beenformed from laminations or layers of flexible or plastic materialimpregnated with a phenolic condensationprodusct and and are} avoided bythe present invention due to molding, casting or pressing of theelements, or element sections,- directly from the plastic -ma-.terial,.as distinguished from building up a laminate,. structure andimpregnating it and as dis tinguished from employing means other than Byforming airplane structural elements directly from suitableplasticmaterial the various disadvantages heretofore mentioned areoverconie and the various advantages heretofore enumerated are obtained.In other words, according to the present invention, airplane structuralelements may be standardized and may be manufactured at comparativelylow cost in perfectly streamlined form with smooth outer surfaces devoidof protuberances, and, at the same time, they may be provided readilyand easily with all necessary ribs, flanges, fillets or the like allrequisite strength and rigidity. 1

Without further description it is thought that the features andadvantages of the invention will be readily apparent to those skilled inthe art, and it will of course be understood that changes in the form,proportion and minor details of construction may be restorted to,without departing from the spirit of the invention and scope of theappended claims- I claim:

1. In an aircraft structure, a spar of I-section including a web and endflanges, at least one of said end flangeshaving inturned marginalportions, a plurality of body units formed of plastic material andprovided with marginal portions disposed in overlying relationship. tothe end flange of said spar which has said inturned marginal flanges,the edges of the marginal portions of said body units being disposed inabutting relationship, flanges integral with said body units abuttingthe inturned marginal portions .of the said flange of said spar, andmeans fastening said body unit flanges to the inturned portions of thesaid flange of said spar.

2. .An aircraft structure as set forth'in claim 1 in which the bodyunitshave smooth outer surfaces collectively forming a smooth, contin-Jlous outer surface, and in which intersecting reinforcing ribsintegral. with said units and with each. other and integrated withtheattaching flanges of the units,-extend inwardly from said units.

3. In an aircraft construction, a structural member having a pluralityof faces, body units formed of plastic material and having attachingportions disposed in abutting and overlying relation to the faces of thestructural member, the,

said body units having smooth outer surfaces collectively forming asmooth continuous outer surface and having reinforcing ribs integralwith the units and with the attaching portions of theunits extendinwardly from the unit, and means A fastening the body units .to thestructural member at said attaching poQion.

JOHN\B. THOMSON.

